Can anyone help? We have same issue. but little different scenario.
A customer can exist in multiple territories but for same partner function if a customer assigned explicitly to a territory (XXXXX ) by BP ID, system should not assigned this customer to another Terriroty ZZZZZ based on geenric rule say zip code and region .both Terriroties are mapp to same partner fucntions (e.g. Area Sales Rep). The customer can be in another terriroty say YYYY based on YYYY rule which is mapped for different partner fucntion (Area Manager)